So, the Strathclyde team devised a “targeted delivery
system”, piggy-backing the extract on proteins that carry iron molecules,
which cancer tumours Hoover up.
The lab test on one type of human skin cancer showed 40 per
cent of tumours disappeared after a month of treatment, while an additional
30 per cent shrank.
Dr Christine Dufès, a senior lecturer at the Strathclyde
Institute of Pharmacy and Biomedical Sciences, who led the research, said:
“These are very encouraging results which we hope could pave the way for new
and effective cancer treatments.
“When we used our method, the green tea extract reduced the
size of many of the tumours every day, in some cases removing them
altogether.
"By contrast, the extract had no effect at all when it was
delivered by other means, as every one of these tumours continued to grow.
“This research could open doors to new treatments for what is
still one of the biggest killer diseases in many countries.”
She added: “I was expecting good results, but not as strong
as these.”
Dr Dufès said population studies had previously indicated
that green tea had anti-cancer properties, and scientists had since
identified the active compound as epigallocatechin gallate.
But the Strathclyde researchers were the first to delivery it
in high enough doses to tumours to have an effect.
She explained: “The problems with this extract is that when
it’s administered intravenously, it goes everywhere in the body, so when it
gets to the tumours it’s too diluted.
“With the targeted delivery system, it’s taken straight to
the tumours without any effect on normal tissue.”
Cancer scientists are increasingly using targeted delivery to
improve results, relying on the many different ‘receptors’ that tumours have
for different biological substances.
In this instance, the scientists used the fact that tumours
have receptors for transferrin, a plasma protein which transports iron
through the blood.
The results have been published in the journal Nanomedicine.
The “ultimate objective” was a clinical trial in humans - but
Dr Dufès said that was some way off.
“We have got to optimise the delivery system and therapeutic
effect first,” she said.
Dr Julie Sharp, from Cancer Research UK, said: “A few studies
have shown that extracts from green tea may have some effect on cancer cells
in the lab but this has not yet been backed up by research in humans.”
She added: “It’s far too soon to say if enjoying a cup of
green tea has any wider benefits in combating cancer but we know that a
healthy balanced diet can help to reduce the risk.”
